There is an important need in the study of toxicology of topically-applied and environmental agents for an in vitro system to study their toxic effects on skin. The in vitro systems have the benefit of allowing study of a large variety of substances on an individual specimen. An in vitro system containing all the components of skin allows studies to determine the effects of agents on the various component cell types and cell interactions. This is particularly the case in three-dimensional histoculture systems. The applicant developed a gel-supported, three-dimensional histoculture system that allows the intact growth and toxicity testing of all components of mouse skin, including keratinocytes, dermal fibroblasts and hair follicle cells as well as hair, for periods of 10 days or more (Li, L., Margolis, L.B. and Hoffman, R.M. Proc. Natl. Acad. Sci., In Press). It is proposed here, using the histoculture system and fluorescent dyes that measure cell viability or cell death, to investigate the effects of a series of pesticides, organotins and carcinogens as model compounds to study toxicity and carcinogenesis on all types of histocultured mouse skin and human foreskin as well as on hair growth from the cultured skin. The measurement of the effects of the toxins are greatly enhanced by confocal microscopy which allows the three-dimensional observation of the specimens not previously possible. The effects of at least one compound in vitro have already correlated in vivo using athymic nude mice such that the cytotoxic effects in vitro correspond to an irritation index for these various compounds scored in vivo.